well without moving the hair, i think its faster than the fur shader (at least it was for me. depends on how many layer you add and how many polygones they have)

the vertices movement might be a bit slower, but again, depends on the amount of layers.

but yes, thats a big advantage, you can let the fur react to wind/physic.

EDIT: Actually, if they are seperated models, you can just move the UV map of the fur, depending on the wind/physic again. but then you need to call more function, which might slow it down too.